


Our Final Problem

by WindowRaindrops



Category: Supergirl (TV 2015)
Genre: F/F, Mind Games, Sherlock AU, everyone is a detective, had to write it after Midvale
Language: English
Status: In-Progress
Published: 2018-01-09
Updated: 2018-01-11
Packaged: 2019-03-02 16:08:54
Rating: Mature
Warnings: Graphic Depictions Of Violence
Chapters: 2
Words: 4,185
Publisher: archiveofourown.org
Story URL: https://archiveofourown.org/works/13321761
Author URL: https://archiveofourown.org/users/WindowRaindrops/pseuds/WindowRaindrops
Summary: “You are playing a very dangerous game, Miss Danvers. One that you can’t possibly understand.” Kara’s shoulders tensed as the woman whispered into her ear, red, glossy lips ghosting mere millimeters next to her skin. "If you play with fire for too long, you’re destined to get burned. With all your talents and achievements, I’m afraid this game is one you’re going to have to forfeit.”The piece concluded with a prolonged note, and the audience around the ballroom floor applauded the dancers and musicians alike. All around Kara and Lena, the couples dropped to either a bow or a curtsy, per protocol. Lena took a half-step back to allow room for her bow. Kara just stood there, still and unmoving. Lena gently held Kara’s hand in her own and placed her lips to the back of Kara’s. As emerald eyes met cerulean, Lena’s gaze hardened, her eyebrows furrowing together.“Stay out of this one, Kara. I mean it. Drop it before you or anyone you care about ends up dead by a river bank.”Or the Sherlock Holmes AU that I can't get out of my head.





	1. Every Story Needs a Beginning

**Author's Note:**

> I just had to write this. Inspired by this tumblr post by Comickergirl:
> 
> http://comickergirl.tumblr.com/post/167628438131/i-suspect-i-will-never-get-over-this-episode
> 
> Comments and kudos are always welcome! Hope you all enjoy!

            “You are playing a very dangerous game, Miss Danvers. One that you can’t possibly understand.” Kara’s shoulders tensed as the woman whispered into her ear, red, glossy lips ghosting mere millimeters next to her skin. Kara had only heard that voice twice before, but she could never forget who it belonged to: Lena Luthor. She was sure of it. Their bodies were now flushed with one another, and despite the mask that covered the majority of Lena’s face, her piercing green eyes were unmistakable. Kara was absentmindedly aware of the music played by the orchestra and let Lena take the lead, following wherever she waltzed with enough grace to match her dance partner. “If you play with fire for too long, you’re destined to get burned. With all your talents and achievements, I’m afraid this game is one you’re going to have to forfeit.”

            The piece concluded with a prolonged note, and the audience around the ballroom floor applauded the dancers and musicians alike. All around Kara and Lena, the couples dropped to either a bow or a curtsy, per protocol. Lena took a half-step back to allow room for her bow. Kara just stood there, still and unmoving. Lena gently held Kara’s hand in her own and placed her lips to the back of Kara’s. As emerald eyes met cerulean, Lena’s gaze hardened, her eyebrows furrowing together.

            “Stay out of this one, Kara. I mean it. Drop it before you or anyone you care about ends up dead by a river bank.”

            Before Kara could respond, Lena abruptly released her hand and disappeared into the crowd, not to be seen again for the rest of the night.

*

**Several months earlier**

            Kara Danvers was never one for mornings. Early mornings even less so. Her hair was often a mess, tangled into an unruly blonde crow’s nest of curls; her dog themed pajamas was occasionally stained with drool on the collar; and to boot, she never could find where her glasses were right away, always thrown haphazardly around the room before a deep slumber.

            If the lack of cruel sunshine beating down on her senses was any indication, it wasn’t even brunchtime. And yet, there was the voice of her older sister, as loud and commanding as ever, demanding that she wake up in this ungodly hour.

            “Kara, we’ve got a client! If you don’t wake up and get your ass off the bed in five seconds, I’m going to eat all of the cookies in the pantry!”

            That got her up in a hurry. She snatched the glasses that she thankfully had the presence of mind to place there last night before passing out, stripped off her corgi pajamas, shrugged on a loose fitting t-shirt and shorts, and ripped the door open to find an amused Alex Danvers leaning against the wall, glancing at her watch.

            “That was ten seconds, I’m impressed.” Kara promptly ignored her sister and strode past her, making a beeline for the pantry.

            “You better have not touched my cookies,” she muttered under her breath, eliciting a laugh from Alex. Kara emerged from the kitchen with a cookie held tightly between her teeth and one in each hand for the trip.

            “Come on, sleepyhead. Client’s downstairs.” _At seven in the morning? Ugh._ Alex took the lead, bounding over to the living room on the floor below. Her sister followed silently, if not still a bit dazed from her sudden awakening. The wooden floorboards creaked with each step they took, groaning from its age and weight they had to support over the years. On the walls, countless framed photos from their childhood lined the walls. One from Alex’s state senior soccer tournament; another from Kara’s science fair with her proudly clutching a glistening first place trophy; pictures from their respective graduations, both high school and beyond; Kara and Alex smiling brightly, ice cream plastered all over their mouths; and an action shot of the two of them mid kick during a taekwondo practice.

            With so many memories like these, Kara sometimes forgot that she was adopted. The Danvers (Eliza and Jeremiah included, not just Alex) had been so kind to her and so readily accepted her as a part of their family that it slipped her mind from time to time. Of course, that’s not to say that she wasn’t painfully cognizant of her biological parents’ absence. Kara lost count of the number of times Alex, Eliza, and Jeremiah had burst in through her door to comfort her during nights when nightmares plagued her mind. Through more time under the Danvers’ care and through therapy, the nightmares subsided to a more manageable frequency. She still had trouble with them now, but instances occurred sparingly, with months in between each.

            As much as they teased each other, Kara was incredibly thankful for Alex. She had been there for her through the bad nights, the good days, and everything in between. Kara tried her absolute best to return that favor whenever she could. She would run through a brick wall for Alex if she asked. Biological sister or not, Alex still was her sister, and Kara wouldn’t trade Alex for anyone else in the world. They were inseparable from one another, their business being a prime example of their close bond. Once Kara had set her mind on the project, Alex immediately dropped everything and joined her in the venture. If anything, for Kara’s safety and genuine interest on her part. Ever since their escapades as teenagers, the sisters became enamored with detective work, reading every Nancy Drew and Agatha Christie book in existence, spending late nights on the family computer looking up whatever they could on investigative techniques, and saving up money for buying ‘proper’ detective equipment. Well, as proper as a teenager can get their hands on.

            Over time, their shared passion for sleuthing manifested in different ways. Alex took the more practical route between the two of them, acing her MCAT exam and excelling in the top medical school in the nation. She was preparing for her life beyond formal education when the call from Kara came. She packed up her belongings and left for National City the next day.

            Kara, on the other hand, took a less conventional route. It was clear from an early age that she was gifted, graduating way ahead of schedule and completing classes that would make a grad student’s head hurt before she was twenty. Her mind just simply worked on a different plane than her peers. When her classmates saw impossible problems and paradoxical questions, she saw puzzles waiting to be solved. She saw a game. For Kara, no game was ever impossible. All the hints and resources were there; she just needed to be sharp and focused enough to see them and connect the dots. It was this relentless approach to her work that propelled her above and beyond her peers.

            While her classmates took on paid internships and entered the workforce, Kara traveled to the corners of the world, determined to quench her insatiable thirst for knowledge, experiencing and learning as much as she possibly could from hundreds and hundreds of people from around the world. If she didn’t know all there was to know, then how could she possibly get the answers she wanted? More importantly, how could she win the game?

            The first time Kara had dived into the private detective world with Alex in Midvale was exhilarating. A murder mystery? Multiple suspects? Incriminating evidence? Oh golly, she had a field day that with that one. Never before had she felt more in her element in Midvale, despite the Danvers’ best efforts. Sure, with Alex, Eliza, and Jeremiah, Kara felt like she had a family again, but chasing down leads with Alex? Analyzing evidence? That’s when Kara Danvers finally felt like she truly belonged: When she finally felt that she had a reason for being there. She had long struggled with why she was there in the first place; why it hadn’t been her in the accident, why she was the only one who made it out alive. But if she could finally be something other than a burden to people like the Danvers or an oddity to those like her classmates, then that was her reason. She could finally serve a purpose in this life. She could then perhaps, finally be deserving of the life that was cruelly ripped out from her parents and given to her.

            Making their way down to the living room, Kara and Alex saw their client waiting patiently for their arrival, standing by the set of chairs by the fireplace. She was an aging woman, most likely approaching her late sixties.

_Judging by the faint trace of dirt and mud on the side of her shoes, she probably made the trip from up north this morning. It had rained yesterday, but not in National City. That ticket stub from peeking out from her purse is definitely from a train. Keeping in mind the weather from the night prior and the trains usually slated to arrive into King’s Cross before 6:40 AM, that narrows down our options to two cities: Liverpool and Manchester. The slight faded nicks below her knuckles on her left hand are largely consistent with scars obtained by fishermen and their hooks. Liverpool it is then._

_That indent on her ring finger—widow. Just recently too, I might add. She’s been trying to cope; hence the corgi she’s got in the house now and the fur sticking at the fringe of her pants. Clearly, it wasn’t her idea. She doesn’t know how to train the poor puppy, look at the light bite marks on her right hand. Most likely a gift from a relative. A well intentioned son, perhaps. Then the coat; quite an expensive make: upwards of 4000 pounds for one. Her posture, perfectly straight. Fingernails well-manicured. And that smell… Clive Christian’s No. 1. All of this is highly indicative that she’s well off._

_But she’s worried about something. Or someone. The prominent veins in her eyes and the slight discoloration below them. Lack of sleep. And there’s the matter of the red splotches near the back of her neck. She’s been spending of quite a lot of time outside recently which is something that she’s not used to in the past few years._

_Wait. Go back. With a corgi, the fur should be much more consistent on her pants. Double coat, year long shedding. And yet, there are only a few stray hairs sticking to the bottom of the pant leg. It’s the dog. She’s here for the dog._

            “Thank you for waiting, Ms.?” Alex stuck out her hand for a standard greeting.

            “Ferrier.” The client gladly took her hand, applying delicate pressure.

            “Please, have a seat Ms. Ferrier.” The older Danvers gestured to the cushioned chairs that laid out before them. “Tea?”

            Ms. Ferrier held up a hand, declining politely. “No thank you.”

            “Well, I’m Alex and that’s Kara.” The blonde offered a small wave. “Pleasure to make your acquaintance.”

            “Likewise.”

            “So,” Alex started with a clap of her hands. “What can we do for you Ms. Ferrier?”

            “First, I’d like to thank you both for agreeing to meet with me on such short notice. I do know that there is normally a queue for potential clients.”

            Kara waved her off. “That’s no problem. As long as the case proves to be interesting, anyways. I trust that your train ride here was a pleasant one?”

            “Yes, yes of course. The reason I came to you this morning has to do with a missing dog of mine.”

            “The corgi?” Kara asked. She was met with a set of wide eyes from Ms. Ferrier.

            “I, well, yes. The corgi.” Ms. Ferrier stumbled out. “It’s been missing for about two days now, and I can’t help but worry over it.”

            “Have you tried contacting the relevant authorities?” Alex re-entered into the conversation.

            “No. The thing is, it was a gift from my son, but originally, it belonged to the family of a prominent political figure in our country. He had to pull a lot of favors to get his hands on the puppy, champion bloodline and all that, so I’d prefer if this was kept under wraps. Wouldn’t want my mistake to reflect badly on my son.”

            “Do you remember the last time you saw the dog?”

            “I believe it was about seven thirty at night on Tuesday, coming home from a walk we take after supper. Once we got back into the house, it ran off to do God knows what. Whatever dogs do in their free time I suppose.”

            Alex nodded along, taking notes as Ms. Ferrier went on. She was going to ask a follow up question, but she was interrupted by a certain Scotland Yard detective who had just ran up the stairs into the living room.

            “Now after that—”

            “Danvers,” called out Detective Maggie Sawyer.

            The two sisters perked up their heads. “Which one?” They asked in unison.

            “Both of you. Body near the Luthor Corp factory in Gotham.”

            Kara rose to her feet immediately, grabbing her coat and Alex’s from the rack. Alex shot Ms. Ferrier an apologetic look before getting up as well.

            “I’m terribly sorry to cut the meeting short, but we’ll get to your case in the earliest convenience. I’ll call you from this number later today for some more questions.” Alex offered her a business card.

            “Yes, I completely understand. I can’t imagine how busy you two must be; Britain’s finest detectives.” She replied, taking the card in her hand.

            “Ha! You hear that, Sawyer? Britain’s finest!”

            “Yeah, whatever Danvers. Just get in the car.” And with that, they were gone. Ms. Ferrier regarded the business card carefully before putting it into her purse and heading out as well. On her way out, she took another glance at the sign that adorned the door:

**Danvers Detective Agency**

**221B Baker Street**

 


	2. Perhaps Too Impulsive

**Summary for the Chapter:**

> And we approach our first crime scene! Also, an appearance from someone!

**Notes for the Chapter:**

> Lol I lied, here's an update. It's a short one, but hey, it's here. As always, comments and kudos are welcome!

            “Kara, can we listen to something other than Jesse McCartney? Please?” Alex’s hand hovered over the aux cable, ready to change the song at a moment’s notice if her sister gave her the go ahead.

            “But Beautiful Soul is a classic!” Kara defended herself from the back seat.

            “Jesse McCartney is only a slightly better version of Justin Bieber. There. I said it.” Alex blurted out.

            Kara let out an incredulous gasp. “You take that back!” She leaned forward in her seat, daring her sister to take on the challenge.

            “Nope. Not a chance.”

            The other half of the Danvers Detective Agency looked to Maggie for support.

            “Sorry, little Danvers. I’m with your sister on this one,” she shrugged, glancing back briefly at Kara before returning her gaze back on the road. With an annoyed huff, Kara slumped back in her seat and promptly caught her phone that Alex threw back.

            “Two against one isn’t fair,” she mumbled, turning her attention to her phone and pulling up the message app.

            For the rest of the car ride to the Gotham, they listened to Alex’s choice of music. While Kara was still pouting about her defeat, she couldn’t help but nod her head to the beat, absentmindedly. She might have not looked like she was listening to Maggie and Alex’s conversation, but one thing about Kara Danvers is painfully clear if you’ve ever met her: she’s always paying attention.

            She heard the way Alex laughed a half a second too long at Maggie’s quips; saw the way Maggie tried to act like she wasn’t stealing glances at Alex when she checked her blind spots; saw the cheeks of her sister flush a shade darker when their fingertips brushed against each other. Kara smiled to herself. Knowing Alex, her heart was probably threatening to break out of its cage right now.

            After a nearly hour-long car ride, the trio arrived at the Luthor Corp factory situated in Gotham. The city donned its usual shroud of fog and gloomy weather. Unlike the city it housed itself in, the factory was a bright white building that housed some of the world’s finest cutting edge technology. It was a stark contrast to the World War II era and gothic inspired edifices that littered Gotham. If anything, it was jarringly sterile.

            There were local police at the scene already, keeping ordinary citizens away from the crime scene. The police tapes were up, but that didn’t seem to deter the horde of reporters and paparazzi who rushed to get the scoop on the latest Luthor family dirt. As Kara, Alex, and Maggie hopped out of the car, the Scotland Yard detective let out a frustrated groan.

            “All these fucking reporters whenever a Luthor is involved in anything. I swear they attract all the bad press in the world.”

            Making their way through the crowd of onlookers and reporters, the detectives were tight-lipped, ignoring the frantic onslaught of questions from the media. Maggie flashed her badge at the officer in front of the tape, and they were let through, holding up the tape high enough for the three of them to enter the crime scene.

            When the body was in sight, Kara stuttered in her tracks. Alex turned to her sister with a worried look.

            “Kara, what’s wrong?”

            The younger Danvers sister shook her head and tugged on the sleeve of Maggie’s jacket, getting her attention.

            “Forensics.” Kara said.

            “Hmm? Oh right. God, they never listen, do they?” Maggie offered her a bright smile before shifting her face into a scowl in an instant. She strode forward with her commanding presence and started to bark out orders. “How many times do I have to tell you wankers, don’t touch the bloody crime scene before the Danvers get here!” The members of the forensics team all jumped back in response, and damn near scurried away from the body. They didn’t dare cross Detective Sawyer, especially if she was pissed. During the Danvers’ first investigations with Scotland Yard, the rest of the unit was reluctant to relinquish their jurisdiction and control. However, after shut case after shut case, they stopped questioning their value and importance.

            Kara stepped closer to the body, accepting a pair of latex gloves from Maggie, per procedure.

            “Our victim is a Joe Henson, a 45 year old…” Maggie started, but her voice faded out in Kara’s ears. It was time to focus.

            _Marks around the eyes consistent with constant use of industrial goggles in the workplace. Yet, an absence of callus on the fingertips that one would expect from hard labor in a factory. Constricted pupils indicative of a long exposure to bright lights. Or in this case, the florescent lighting and glimpses of laser fire. Couple all of this with the areas of expertise of Luthor Corp and you can make an educated guess that he was developing computer hardware here. Coin toss between memory and core processors._

_Married, but not faithful. Dry skin and the red abrasions around the ring suggest repeated removal of the object. Cologne on too strong. Would seem he was aiming to impress someone with the scent. Hardly needed in an industrial factory._

_Now to the cause of death. A single bullet to the chest, fired precisely at his heart, probably completely shredding his aorta and atrium. Fired from the front, indicated by the blood splatter on the pavement. The size of the entry wound is unusually large. Fired from the front, at close range. Huh. Close range. The faint ring around the wound is strange absent of gunshot residue and wider than normal. The gun was fired from a silencer._

“…a 45 year old manager of the memory card and encryption development team at the factory—”

            Kara abruptly stood up. “Time of death?”

            “Uh, around 9 pm. Why? Find anything?”

            “Alex, you didn’t see any shell casings on the ground, did you?”

            Her sister regarded the question for a moment, casting a quick sweep of the crime scene to make sure. “Now that you mention it, I haven’t.”

            “See the entry wound?” The trio leaned in.

            “It’s bigger than I expected,” Alex added.

            “Right. Which means that our victim personally knew the killer. With all the streetlights next to facility,” Kara pointed to the ones that lined the street. “The shooter’s face would have been unmistakable.”

            “Seems like our victim was caught off guard when he was shot.” Maggie concluded, which Kara agreed with, nodding along. She continued, “the gunshot residue is also more scattered than one would expect,” making an oval motion with her finger. “I’d guess the bullet was fired through a silencer.”

            “And with the lack of shell casings on the ground, it’s very likely that the killer knew their stuff,” Alex crossed her arms, frowning at the possibility. This might be more complicated than she had originally thought.

            “The cameras were all fried at the time of the murder too. Looks like they had help,” Maggie said.

            “Maybe,” Kara muttered in a non-committal manner. Right then, a forensics team member came bounding towards them with a shattered phone sealed in an evidence bag. Kara took it in her hands, feeling the weight of the device in her hands. She seemed on edge, constantly checking her watch.

            “He’s late,” Kara murmured.

            “Who’s late?” Alex asked.

            At that moment, a certain boyish voice rang out from the crowd outside the crime scene.

            “Hey, hold on! I was told to be here! I have rights, you know!”

            They turned towards the commotion and when Kara caught sight of the person making all the noise, she sported a half smile and called out, “let him through! He’s with me.”

            “Wait, what?” Maggie and Alex blurted out in unison.

            “Kara, who the hell is that?” Alex followed up.

            The man, if you could call him that, was a bit of a mess. Tussled hair, crooked tie, ruffled collar, a gigantic messenger bag slung over his shoulder. Nevertheless, he was all smiles as he ran towards them. He began profusely apologizing when he within an arm’s distance.

            “I’m so sorry, Miss Danvers. I got here as soon as I got your text, but the traffic was pretty bad.”

            “No worries. Call me Kara.”

            “Okay, Kara it is. And you must be the other Miss Danvers! So nice to meet you!” He offered his hand for a greeting, but rescinded his offer once he noticed the death glare Alex was sporting. “Never mind then. And you must be?”

            “Kicking you out of a crime scene. I don’t know what little Danvers told you, but this area is for authorized personnel only.” Maggie grabbed his shirt collar and began to pull him back towards the tape.

            He let out an indignant yelp and looked to the blonde for support. “Kara!”

            “Just wait outside the taped area; I’ll be right there.”

            Once they were a few yards away, Alex grabbed Kara’s attention. “Kara, seriously who the hell was that?”

            “That was Winn.” As if that was sufficient enough.

            “Okay…why is Winn here?”

            “I hired him. As an intern.”

            “An intern?” Alex damn near exploded. “Kara, why did you hire an intern?”  

            “Well, we’re handling more cases now, so our workload can be overwhelming at times, so I though we could use one to help with the more menial tasks. And he is a computer whiz. Tested him out myself.”

            “Why didn’t you talk to me about this?”

            “Couldn’t find the right opportunity,” Kara shrugged. “I’m sorry, Alex. It’s not that I wanted to go over you or anything like that, it’s just that I got fixated on this and just…did it, you know? I won’t do it again, I promise. Last impulsive thing this year, I swear.”

            Alex snorted. “Yeah, right.” Alex sighed deeply, pinching the bridge of her nose. “I suppose we can’t fire him now. At least not right away.”

            “So, you’ll give him a chance?”

            “Maybe. I’m thinking about it.”

            “Then think faster because I want him to look at the corrupted video files from the security cameras.”

            Maggie joined their conversation. “Little Danvers, you can’t just bring whoever you want to a crime scene. There are rules here.”

            Kara wanted to interject to defend herself. “But you let—”

            “I’m not done.” Kara snapped her mouth shut. “I may give you a lot of leeway when it comes to solving crime because you get results and you’re a good kid, but this is still my crime scene, you understand? There are standards and procedures that everyone has to follow. I don’t care what you and your sister decided to do regarding your business, but when you’re here, under my jurisdiction and responsibility, you follow my lead, got it?”

            “Yeah. I’m sorry Maggie.”

            “As long as you understand where I’m coming from. He can tag along but outside the crime scene.” Kara nodded in agreement.

            “Anything else you haven’t told us?” Alex asked, her arms still crossed over her chest.

            Kara scratched her head and nodded sheepishly. “I might have agreed to let him rent a room downstairs.”

            “YOU DID WHAT?”

**Notes for the Chapter:**

> Thanks for reading! Please bear with me as I try to weave (or butcher) Sherlock Holmes and Supergirl to how I see fit.
> 
> Tumblr: window-raindrops
> 
> See you in like 4 days (maybe). What even is a regular update schedule?

**Author's Note:**

> The next chapter might not be out for a week or two because I want to get a head start on writing this one and the Jason Bourne AU. Also, I'm taking liberties with the geography, just bear with me here.
> 
> My tumblr is: window-raindrops. Come yell at me about Supercorp!
> 
> Thanks for reading!


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